System for burn-in testing of electronic devices

ABSTRACT

A system is provided which allows for burn-in testing of electronic devices wherein power current is provided individually to each one of the electronic devices. The system also includes various connectors, cables, and other configurations that allow for power currents having large magnitudes to be provided to the electronic devices.

CROSS-REFERENCE TO OTHER APPLICATIONS

This Application is a division of U.S. patent application Ser. No.10/184,525, filed on Jun. 27, 2002 now U.S. Pat. No. 6,815,966.

BACKGROUND OF THE INVENTION

1). Field of the Invention

This invention relates generally to a system for burn-in testing ofelectronic devices.

2). Discussion of Related Art

When fabrication of electronic devices, such as computer processors andmemories, has been completed, the electronic devices are subjected toburn-in and electrical tests in order to identify and eliminatedefective devices before shipment to customers. The term “burn-in”relates to operation of an integrated circuit at a predeterminedtemperature or temperature profile, typically an elevated temperature inan oven. Certain operating electrical bias levels and/or signals aresupplied to the electronic devices while they are at the elevatedtemperature. The use of the elevated temperature accelerates stress towhich the devices are subjected during bum-in, so that marginal devicesthat would otherwise fail shortly after being placed in service failduring burn-in, and are eliminated before shipping.

The electronic devices are usually located within burn-in sockets thatare mounted to a burn-in board substrate. The burn-in board substrate isthen inserted into an oven, and edge fingers on the burn-in boardsubstrate are inserted into an edge finger socket in a rear of the oven.A driver board assembly is located externally of the oven, and isconnected to the edge finger socket on a feedthrough board. Signalcurrents are provided from the driver board assembly through thefeedthrough board, the edge finger socket on the feedthrough board, andthe edge fingers to the electronic devices in the sockets on the burn-inboard substrate. Power current is also provided from the driver boardassembly through the socket and the edge fingers to the electronicdevices.

The magnitude of the power that can be provided through edge fingers isgenerally relatively small, typically on the order of 3 to 5 A perfinger. Certain devices, for example, computer processors, now requirepower currents having larger magnitudes than what can practically beachieved through edge finger connectors. In many cases, it may also berequired to monitor power current that is provided to each individualdevice. Existing systems, however, are not adapted for providingindividual power current to individual devices, and therefore also donot lend themselves to monitoring of power currents that are providedindividually to each electronic device per finger.

Another disadvantage of using edge finger connectors is that they canonly be located on an edge of a substrate, and therefore provide alimited amount of real estate for adding additional signal, power,ground, and other lines.

BRIEF SUMMARY OF THE INVENTION

Generally speaking, a system is provided which allows for burn-intesting of electronic devices wherein power current is providedindividually to each one of the electronic devices. The system alsoincludes various connectors, cables, and other configurations that allowfor power currents having large magnitudes to be provided to theelectronic devices.

According to one aspect of the invention, a burn-in board assembly isprovided. The burn-in board assembly has a burn-in board substrate, aplurality of burn-in sockets on the burn-in board substrate, each toreceive a respective electronic device. The burn-in board assembly alsohas a plurality of burn-in board signal connectors on the burn-in boardsubstrate. Each burn-in board signal connector has a surface forreleasably mating with a respective surface of a respective signalcontact. Each signal connector is capable of carrying maximum directcurrent having a first magnitude. (Direct-current ratings are usedthroughout this description, although it should be understood that theconnectors that are so characterized herein may carry direct current oralternating current.) The burn-in board assembly also has a plurality ofburn-in board signal conductors. Each signal conductor connects theburn-in board signal connectors to signal contacts on the devices. Theburn-in board assembly also has a plurality of burn-in board powerconnectors secured to the burn-in board substrate. Each burn-in boardpower connector has a surface for releasably mating with a respectivesurface of a respective power contact. Each power connector is capableof carrying maximum direct current having a second magnitude which islarger than the first magnitude. The burn-in board assembly also has aplurality of burn-in board power conductors. Each burn-in board powerconductor connects each burn-in board power connector individually to arespective burn-in board power contact on a respective one of thedevices.

The second magnitude may be at least 7 A. The second magnitude may be atleast 1.5 times the first magnitude. The second magnitude may be atleast 4 A more than the first magnitude.

The burn-in board power conductors are preferably capable of carryingmaximum direct current of a magnitude which is larger than the firstmagnitude.

Burn-in board power conductors preferably connect at least five of theburn-in board power connectors individually to at least five of thedevices. More preferably, the burn-in board power conductors connect atleast 10 of the burn-in board power connectors individually to at least10 of the devices.

The burn-in board signal connectors and the bum-in board powerconnectors may be different types of connectors. The burn-in boardsignal connectors may, for example, be edge fingers. The surface of eachburn-in board power connector may, for example, be cyndrical, preferablycircular cylindrical, such as when the burn-in power connector is arespective pin.

The bum-in board signal connectors and the burn-in board powerconnectors may be in two distinct groups. The burn-in board assemblymay, for example, include a burn-in board power connector block with theburn-in board power connector secured to the burn-in board power block,and the burn-in board power connector block being secured to the burn-inboard substrate independent from the burn-in board signal connectors.The bum-in board assembly may also include a burn-in board daughtercard, with the burn-in board power connector being secured to theburn-in board daughter card, and the burn-in board daughter card beingsecured to the substrate independent from the burn-in board signalconnectors. Portions of the burn-in board power conductors may formtraces, the traces spreading from one another from the burn-in boardpower connectors to locations where the burn-in board power conductorsleave the burn-in board daughter card. The traces may spread by at least25%.

Preferably, movement of the bum-in board substrate in an insertiondirection causes engagement of the burn-in board signal connectors withthe signal contacts and engagement of the burn-in board power connectorswith the power contacts. In such a case, the bum-in board powerconnectors may be pins, and the burn-in board signal connectors may beedge fingers.

Preferably, the signal contacts are at the same locations on at leasttwo of the devices, and the power contacts are at the same locations onthe two devices.

According to another aspect of the invention, a burn-in board assemblyis provided, having different types of connectors. A plurality ofburn-in board signal edge finger connectors and a plurality of burn-inboard power conductors may be secured to a burn-in board substrate,wherein each burn-in board power conductor has a cylindrical contactsurface. The cylindrical contact surface may, for example, be circularcylindrical. In one embodiment, the burn-in board power conductors maybe pins. An embodiment is also contemplated wherein the burn-in boardpower conductors are holes that mate with pins, but such an embodimenthas the disadvantage that the pins cannot be maintained as easily aswhen they are located on the burn-in board substrate.

According to another aspect of the invention, a burn-in testing driverassembly is provided. The burn-in testing driver assembly includes adriver substrate, a plurality of driver signal connectors secured to thedriver substrate, signal electronics, a plurality of driver powerconnectors secured to the driver substrate, and a power supply. Eachdriver signal connector has a surface for releasably mating with arespective signal contact. Each driver signal connector is also capableof carrying a maximum direct current having a first magnitude. Eachdriver power connector has a surface for releasably mating with arespective power contact. Each driver power connector is also capable ofcarrying maximum direct current having a second magnitude which islarger than the first magnitude. The power supply is connected to thedriver power connectors.

The second magnitude may, for example, be at least 7 A. The secondmagnitude may, for example, be at least 1.5 times the first magnitude.The second magnitude may, for example, be at least 4 A more than thefirst magnitude.

The driver signal connectors and the driver power connectors may bedifferent types of connectors. The driver signal connectors may, forexample, be within an edge finger connector block. The surface of eachdriver power connector may, for example, be substantially circular, suchas in the case where each driver power connector is a respective pin.

The driver signal connectors and the driver power connectors may be intwo distinct groups. The burn-in testing driver may, for example,further include a driver power connector block, with the driver powerconnectors being secured to the driver power connector block, and thedriver power connector block being secured to the driver substrateindependent from the driver signal connectors. The burn-in testingdriver may, for example, further include a driver power board, with thedriver power connector being secured to the driver power board, and thedriver power board being secured to the driver substrate independentfrom the driver signal connectors.

Preferably, movement of the driver substrate in an insertion directioncauses engagement of the driver signal connectors with the signalcontacts and engagement of the driver power connectors with the powercontacts.

The burn-in testing driver may further include a plurality of drivercurrent detectors and an output device. Each detector may be incommunication with a respective one of the driver power connectors todetect current separately through each one of the driver powerconnectors. The output device may be in communication with the drivercurrent detectors to provide an output of the respective currentsthrough the respective driver power connectors.

According to a further aspect of the invention, a burn-in testing driverassembly is provided, having a driver substrate, a plurality of driversignal connectors, signal electronics, a plurality of driver powerconnectors, a power supply, a plurality of driver current detectors, andan output device. The driver signal connectors are secured to the driversubstrate. Each driver signal connector has a surface for releasablymating with a respective signal contact. The signal electronics isconnected to the driver signal connectors. The driver power connectorsare secured to the driver substrate. Each driver power connector has asurface for releasably mating with a respective power contact. The powersupply is connected to the driver power connectors. Each detector is incommunication with a respective one of the driver power connectors todetect current separately through each one of the driver powerconnectors. The output device is in communication with the drivercurrent detectors to provide an output of the respective current throughthe respective driver connectors. The output device may, for example, bea microcontroller that provides an output indicative of the magnitudesof the respective currents to a computer.

Preferably, power current provided by the power supply to a plurality ofthe driver power connectors is shut down if a current detected by asingle driver current detector exceeds a predetermined maximum.Preferably, power current to at least 10 of the driver power connectorsis shut down. Power current may be shut down by shutting down the powersupply.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of example with reference tothe accompanying drawings, wherein:

FIG. 1 is a side view illustrating a system, according to an embodimentof the invention, that is used for burn-in testing of electronicdevices;

FIG. 2 is perspective view illustrating a portion of a burn-in boardassembly forming part of the system;

FIG. 3 is a top plan view illustrating further components of the burn-inboard assembly;

FIG. 4 is a top plan view illustrating contact layouts on two of theelectronic devices;

FIG. 5 is a top plan view illustrating a portion of the burn-in boardassembly, and further illustrating a feedthrough assembly and a portionof a burn-in testing driver board assembly forming part of the system;

FIG. 6 is a side view of the components or portions of componentsillustrated in FIG. 5; and

FIG. 7 is a top plan view illustrating further components of the driverboard assembly.

DETAILED DESCRIPTION OF THE INVENTION

System Overview

FIG. 1 of the accompanying drawings illustrates a system 10 that is usedfor burn-in testing of electronic devices, according to an embodiment ofthe invention. The system 10 includes a housing 12, a plurality ofburn-in testing driver board assemblies 14, a plurality of feedthroughassemblies 16, a plurality of burn-in board assemblies 18, a heater 20,and a computer system 22.

The housing 12 has an outer wall 24, two inner walls 26 and 28, and adoor 30. An oven area 32 is defined jointly by the inner wall 26, thedoor 30, and a portion of the outer wall 24. A wall cavity 34 is definedjointly by the inner walls 26 and 28 and another portion of the outerwall 24. A driver cabinet 36 is defined jointly by the inner wall 28 andanother portion of the outer wall 24 on a side of the wall cavity 34opposing the oven area 32.

Each burn-in board assembly 18 has a respective burn-in board substrate38 and a plurality of burn-in sockets 40 mounted to the burn-in boardsubstrate 38. Each burn-in socket 40 is capable of receiving arespective electronic device for purposes of burning in and/or testingthe electronic device. Each burn-in board assembly 18 also has arespective electronic interface 42 on a left side thereof.

Each feedthrough assembly 16 has a respective feedthrough board 46,additional feedthrough cables 48 mounted to the feedthrough board 46,and opposing electronic interfaces 50 and 52. The feedthrough assemblies16 are located within the wall cavity 34 and form a bridge between theoven area 32 and the driver cabinet 36. The electronic interfaces 50 arepositioned on the right of the feedthrough assembly 16 in the oven area32, and the electronic interfaces 52 are positioned on the left in thedriver cabinet 36.

Each bum-in testing driver board assembly 14 has a respective driverboard substrate 56 and electronics (not shown) mounted directly andindirectly to the driver board substrate 56. The electronics includesignal, power, and ground electronics that can be used to test theelectronic devices held by the bum-in sockets 40. Each driver boardassembly 14 also has a respective electronic interface 58 on a rightside thereof.

When assembling the system 10, each driver board assembly 14 is moved inan insertion direction 60 into the driver cabinet 36. The electronicinterface 58 of each driver board assembly 14 mates with an electronicinterface 52 of a respective feedthrough assembly 16. The feedthroughassemblies 16, together with the driver board assemblies 14 connectedthereto, form a permanent or semi-permanent driver subsystem that isused for testing multiple sets of electronic devices that aresubsequently received by the bum-in board assemblies 18.

The door 30 is then opened and any of the burn-in board assemblies 18 inthe oven area 32 are removed from the oven area 32. A respectiveelectronic device is then inserted into each one of the burn-in sockets40. The burn-in board assemblies 18 are then again moved in an insertiondirection 62 into the oven area 32. A respective electronic interface 42of each burn-in board assembly 18 mates with an electronic interface 50of a respective feedthrough assembly 16.

The heater 20 is then operated so that the oven area 32 heats to atemperature required for burning in and/or testing the electronicdevices. The heater 20 is shown as being within the oven area 32 forpurposes of simplicity, but in reality is located in a separatededicated area that is in communication with the oven area 32. Theelectronics of the driver board assemblies 14 are insulated, and so areprotected, by the wall cavity 34 from heat in the oven area 32. Acomputer system 22 is connected to each one of the driver boardassemblies 14. The computer system 22 is used to operate the electronicsof the driver board assemblies 14 so that the electronics of each driverboard assembly 14 provides signal, current, and ground through arespective feedthrough assembly 16 and a respective burn-in boardassembly 18 to the electronic devices held by the sockets 40 of therespective burn-in board assembly 18. The electronic devices are testedwhile simultaneously being stressed with heat from the heater 20 andwhile the performance of each electronic device is monitored by thecomputer system 22. Monitoring and pass/fail detection is done bycircuitry on the driver board assembly 14, and these results arereported back to the computer system 22.

The burn-in board assemblies 18 are disengaged from the feedthroughassemblies 16 after burn-in testing is completed, and the electronicdevices are replaced with a subsequent set of devices that have to betested.

As will now be further described, the system 10 includes components thatallow for power current to be provided individually to each one of theelectronic devices mounted to the sockets 40 of a respective burn-inboard assembly 18. The components that allow for power current to beprovided individually to each electronic device further allow formonitoring of power current provided to each electronic deviceindividually. The components also allow for currents having largermagnitudes to be provided to the electronic devices than would bepossible without the components.

Burn-In Board Assembly

FIG. 2 illustrates a portion of one of the burn-in board assemblies 18.The burn-in board assembly 18, in addition to the burn-in boardsubstrate 38, further includes a burn-in board daughter card 68, 24conductive power posts 70P, conductive ground posts 70G, burn-in boardsignal edge finger connectors 72, and a burn-in board power/groundconnector 74.

Lower ends of the conductive power posts 70P are secured to the burn-inboard substrate 38. The burn-in board daughter card 68 is secured toupper ends of the conductive power posts 70P, so that the burn-in boarddaughter card 68 is spaced from the burn-in board substrate 38.

The burn-in board power/ground connector 74 includes a burn-in boardpower/ground connector block 76 and 46 burn-in board conductor pins 78secured to the burn-in board power/ground connector block 76. (There is,in fact, a 47^(th) pin, but it can be ignored for purposes of furtherdiscussion.) The 46 burn-in board conductor pins 78 include 24 burn-inboard power conductor pins 78P and 22 burn-in board ground conductorpins 78G. The burn-in board conductor pins 78P and 78G all have circularcylindrical outer surfaces. The burn-in board power/ground connectorblock 76 is secured to an upper surface of the burn-in board daughtercard 68. A spacing between a first and a last of the conductive powerposts 70P is approximately twice a spacing between a first and a last ofthe burn-in board power conductor pins 78P.

The burn-in board signal edge finger connectors 72 are all located onupper and lower surfaces at an edge of the burn-in board substrate 38.The burn-in board signal edge finger connectors 72 can each carry amaximum direct current of either 3 A or 5 A. The burn-in board conductorpins 78P and 78G can carry maximum direct current of approximately 10 Aeach.

Edge finger socket blocks 80 may be mounted on opposing sides to theburn-in board substrate. The edge finger socket blocks 80, together withthe edge finger connectors 72, can be used to form a high-densityinterconnect scheme such as that described in U.S. Pat. No. 5,429,510.

FIG. 3 illustrates the burn-in board assembly 18 with, in the presentexample, 24 electronic devices 82 located thereon. The electronicdevices 82, in the present example, are located in six columns atincreased distances from the burn-in board daughter card 68, with fourof the electronic devices 82 in each column.

Power traces 84 are formed on the burn-in board daughter card 68. Eachtrace 84 connects a respective burn-in board power conductor pin 78P toa respective conductive power post 70P. The traces 84 spread from wherecurrent enters the burn-in board daughter card 68 at the bum-in boardpower conductor pins 78P to where current leaves the bum-in boarddaughter card 68 at the conductive power posts 70P.

Respective power traces 86 are formed in the burn-in board substrate 38.Each one of the traces 86 connects a respective one of the conductivepower posts 70P to a respective power contact of a respective one of theelectronic devices 82. Because power current is provided independentlyto each one of the electronic devices 82, there is a total of 24 of thetraces 86, each trace 86 connecting a respective post 70 to a respectiveelectronic device 82. The spreading of the current as facilitated by thetraces 84 reduces the requirement for many power planes to accommodatethe relatively large number of traces 86.

What should be noted is that each one of the burn-in board powerconductor pins 78P provides independent power individually to arespective one of the electronic devices 82 through a respective burn-inboard power conductor formed by a respective one of the traces 84, arespective one of the conductive power posts 70P, and a respective oneof the traces 86. There is a one-to-one relationship between the numberof burn-in board power conductor pins 78P and the number of electronicdevices 82. Each respective burn-in board power conductor can carry amaximum direct current of 10 A to a respective one of the electronicdevices 82.

It can thus be seen that the burn-in board power conductor pins 78Pallow for bypassing of the limited current-carrying capabilities of theburn-in board signal edge finger connectors 72.

Three ground shunt bars 88 are formed at spaced locations along thewidth of the burn-in board daughter card 68. Each one of the 22 burn-inboard ground conductor pins 78G is connected to one of the ground shuntbars 88. Each ground shunt bar 88 is connected to a plurality ofconductive ground posts 70G (FIG. 2). Ground traces 90 are formed in theburn-in board substrate 38, and are all connected to the conductiveground posts 70G. The traces 90 are also connected to one another, sothat the burn-in board ground conductor pins 78G form a common terminal.The traces 90 are also connected to ground contacts on each one of theelectronic devices 82.

Signal traces 92 in the burn-in board substrate 38 connect a respectiveone of the burn-in board signal edge finger connectors 72 in parallelwith signal contacts on all the electronic devices 82. Separate ones ofthe burn-in board signal edge finger connectors 72 are connected toseparate contacts on a respective one of the electronic devices 82. Somesignal traces (not shown) are also connected individually to individualoutput pins, typically one or two pins, of the electronic devices 82 togive a pass/fail result for each device individually.

FIG. 4 illustrates the contact layout on two of the electronic devices82. It can be seen that the contact layouts are identical. Bothelectronic devices 82 have power contacts at the same locations, andindividual power current is provided to each electronic device 82. Bothelectronic devices 82 have ground contacts at the same locations, and acommon ground is provided to both electronic devices 82. Both electronicdevices 82 also have signal contacts at the same locations. A firstsignal (Signal 1) is provided to the same locations on the electronicdevices 82. Similarly, a second signal (Signal 2) is provided to thesame locations on both electronic devices 82, and a third signal (Signal3) is provided to the same locations on both electronic devices 82.

Feedthrough Assembly

Referring now to FIGS. 5 and 6, each feedthrough assembly 16, inaddition to its feedthrough board 46 and feedthrough cables 48, furtherincludes a feedthrough edge finger connector block 94, feedthrough edgefingers 96, and right and left feedthrough socket blocks 98 and 100,respectively.

The feedthrough edge finger connector block 94 is mounted to aright-hand edge of the feedthrough board 46. The feedthrough edgefingers 96 are all on upper and lower surfaces near a left edge of thefeedthrough board 46. The feedthrough edge finger connector block 94 hasa slot 102 formed therein. Feedthrough signal contacts 104 are formed oninner surfaces of the slot 102. Each one of the feedthrough edge fingers96 is capable of carrying maximum direct current having a magnitude ofeither 3 A or 5 A. A plurality of signal traces 106 is formed on thefeedthrough board 46. Each trace 106 connects a respective one of thefeedthrough signal contacts 104 independently to a respective one of thefeedthrough edge fingers 96. Some of the signal contacts 104 are alsoshorted together, to give higher current.

The right feedthrough socket block 98 is mounted through an intermediatecomponent 108 to the feedthrough board 46, and is positioned slightlyabove the feedthrough edge finger connector block 94. The leftfeedthrough socket block 100 is mounted through an intermediatecomponent 110 to the feedthrough board 46, and is located above some ofthe feedthrough edge fingers 96. Each socket block 98 and 100 has aplurality of circular cylindrical openings 112 formed therein. Eachcircular cylindrical opening 112 is defined by a circular cylindricalconductive contact 114 (FIG. 5) within the respective socket block 98 or100.

Each one of the cables 48 has one end attached to the right feedthroughsocket block 98 and an opposing end attached to the left feedthroughsocket block 100. Each respective cable 48 also connects a respectiveone of the conductive contacts 114 in the right feedthrough socket block98 with a respective conductive contact 114 in the left feedthroughsocket block 100.

As previously mentioned with reference to FIG. 1, the burn-in boardassembly 18 is moved in an insertion direction 62. Movement of theburn-in board assembly 18 in the insertion direction 62 moves each oneof the burn-in board conductor pins 78P and 78G into a respective one ofthe circular cylindrical openings 112 in the right feedthrough socketblock 98. The edge of the burn-in board substrate 38 carrying theburn-in board signal edge finger connectors 72 enters the slot 102shortly before the burn-in board conductor pins 78 begin to enter thecircular cylindrical openings 112 for purposes of controlling insertionforce of the edge into the slot 102. There are two additional alignmentpins 116 that engage first. The additional alignment pins are mechanicalonly, and do not carry any current. Further movement of the burn-inboard assembly 18 in the insertion direction 62 causes further movementof the burn-in board conductor pins 78 into the circular cylindricalopenings 112 while the burn-in board signal edge finger connectors 72move into the slot 102. A respective surface of each one of the burn-inboard signal edge finger connectors 72 then contacts a respectivesurface of each one of the feedthrough signal contacts 104. A conductivecircular cylindrical outer surface of each one of the burn-in boardconductor pins 78 also contacts a respective one of the circularcylindrical conductive contacts 114 in the right feedthrough socketblock 98. A respective one of the feedthrough edge fingers 96 is thenindividually connected to a respective one of the burn-in board signaledge finger connectors 72.

A respective one of the circular cylindrical conductive contacts 114 inthe left feedthrough socket block 100 is also individually connected toa respective one of the burn-in board conductive pins 78P and 78G. Thecircular cylindrical conductive contacts 114 in both feedthrough socketblocks 98 and 100 can be divided into two groups. The first groupconsists of the conductive contacts 114P that are connected to theburn-in board power conductor pins 78P. Each one of the conductivecontacts 114P in the left feedthrough socket block 100 can be used toprovide power current individually to each respective one of theelectronic devices. The second group consists of the conductive contacts114G that are connected to the burn-in board ground conductive pins 78G,to provide ground to the electronic devices.

The conductive contacts 114P and 114G can all carry maximum directcurrent having a magnitude of 10 A. An advantage of connecting theconductive contacts 114P and 114G with the cables 48 as opposed to, forexample, traces, is that cables create less noise due to passiveparameters associated with them. The cables 48 minimize voltage drop,since cables have lower resistance than traces on a circuit board. Thisis increasingly important as the absolute value of the nominal voltagedecreases, especially below 1 V.

Driver Board Assembly

FIGS. 5 and 6 also illustrate a portion of one of the driver boardassemblies 14. The components of the driver board assembly 14 that areshown include a driver substrate 120, a driver power board 122, a driveredge finger connector block 124, and a driver power/ground connector126.

The driver edge finger connector block 124 is secured to an edge of thedriver substrate 120. The driver edge finger connector block 124 has aslot 130 in a side thereof. Driver signal connectors 132 (FIG. 5) arelocated within the slot 130.

The driver power/ground connector 126 includes a driver power/groundconnector block 134 and a plurality of driver connector pins 136 securedto the driver power/ground connector block 134. The driver power/groundconnector block 134 is secured to the driver power board 122, and thedriver power board 122 is secured through an intermediate component 138to the driver substrate 120.

As previously mentioned with reference to FIG. 1, the driver boardassembly 14 is moved in an insertion direction 60. The driver connectorpins 136 move into the circular cylindrical openings 112 in the leftfeedthrough socket block 100. The slot 130 begins to move over an edgeof the feedthrough board 46 carrying the feedthrough edge fingers 96after tips of the connector pins 136 are inserted into the circularcylindrical openings 112 in the left feedthrough socket block 100.Subsequent movement of the driver board assembly 14 in the insertiondirection 60 moves the connector pins 136 further into the openings 112,and the slot 130 all the way over the feedthrough edge fingers 96. Eachone of the driver signal connectors 132 has a respective surface makingcontact with a respective surface of a respective one of the feedthroughedge fingers 96. Each one of the connector pins 136 has a conductivecircular cylindrical outer surface making contact with a respective oneof the circular cylindrical conductive contacts 114 in the leftfeedthrough socket block 100.

The driver connector pins 136 can be divided into two groups. The firstgroup consists of driver power connector pins 136P that engage with theconductive power contacts 114P of the left feedthrough socket block 100.The second group consists of driver ground contact pins 136G that engagewith the conductive ground contacts 114G of the left feedthrough socketblock 100. There can be a one-to-one relationship between the number ofdriver power connector pins 136P and the number of electronic devices,because each one of the driver power connector pins 136P provides powercurrent individually to a respective one of the electronic devices.

FIG. 7 illustrates further components of the driver board assembly 14,including signal electronics 144, a power supply 146, an electric ground148, and an apparatus 150 for monitoring current provided individuallyto each electronic device.

The power supply 146 is connected through a respective resistor 152 to arespective one of the driver power connector pins 136P. There is a totalof 24 of the resistors 152, one for each electronic device. The driverground connector pins 136G are all connected to the electric ground 148.Power current can flow at 10 A from the power supply 146 individuallythrough a respective one of the resistors 152 to respective ones of thedriver power connector pins 136P, and subsequently individually torespective ones of the electronic devices. Return current can flow at 10A from the electronic devices through the electric ground 148.

Signal electronics 144 are connected to the driver board signal contactsconnectors 132. Individual signals can be provided from the signalelectronics 144 individually to respective ones of the driver signalconnectors 132. In general, each driver signal connector 132 providessignal current in parallel to the same locations on all the electronicdevices (see FIG. 4).

The apparatus 150 includes 24 amplifiers 156, a multiplexer 160, aneight-bit analog-to-digital converter 162, a register 164, a bus 166,and a micro-controller 168.

Each amplifier 156 is connected by two detector lines 170 over arespective one of the resistors 152. A change in current through arespective resistor 152 causes a change in voltage over the respectiveresistor 152 according to the equation ΔV=ΔIR. The voltage differenceprovided through the detector lines 170 to the amplifier 156 thusprovides an indication of the magnitude of the current that flowsthrough the respective resistor 152 to the respective electronic deviceto which the respective resistor 152 is connected.

The amplifier 156 provides linear amplification of the voltagedifference detected over the detector lines 170, and provides a voltageoutput to the multiplexer 160. The voltage output provided by theamplifier 156 to the multiplexer 160 has a magnitude that is indicativeof the magnitude of the current flowing through the respective resistor152. The multiplexer 160 receives a total of 24 voltages (V1, V2, V3, .. . , V24). Each voltage input into the multiplexer 160 has a magnitudethat is indicative of a respective current flowing to a respectiveelectronic device.

The multiplexer 160 has an output that is connected to theanalog-to-digital converter 162. Five selector lines 172 are connectedto the multiplexer 160. Signals through the selector lines 172 allow themultiplexer 160 to select one of the voltages (e.g., V3) which isprovided to the analog-to-digital converter 162. Only one of thevoltages V1 to V24 is provided to the analog-to-digital converter 162 ata given moment in time, but signals to the selector lines 172 arecontinually altered to repeatedly step the voltage that is provided tothe analog-to-digital converter 162 from V1 to V24.

The analog-to-digital converter 162 converts the voltage received fromthe multiplexer 160 to eight-bit digital data, and provides the data tothe register 164. The digital data held by the register 164 isindicative of the magnitude of the voltage provided by the multiplexer160 to the analog-to-digital converter 162.

The register 164 is connected through the bus 166 to the microcontroller168. Other registers 174 may also be connected through the bus 166 tothe microcontroller 168. The microcontroller 168 provides a read commandto a select one of the registers 164 or 174 in order to control datathat is supplied to the bus 166. When a read command is provided to theregister 164, the digital data stored in the register 164 is providedthrough the bus 166 to the microcontroller 168.

The computer system 22 is connected to the microcontroller 168. Themicrocontroller 168 provides the digital data to the computer system 22.The computer system 22 can be used to monitor and report the digitaldata and so indirectly monitor the current that is provided to each oneof the electronic devices.

A user also programs the computer system 22 with a reference high leveland a reference low level for the individual channels. The computersystem 22 continually compares the current and measures each of thedriver power connector pins 136P with the reference value. The computersystem 22 takes no action while the power current in each and everypower connector pin 136P is between the reference values. The computersystem 22 initiates action when it is detected that the power currentthrough one of the power connector pins 136P exceeds the reference highvalue or is less than the reference low value. The computer system 22then sends a command through the microcontroller 168, the bus 166, andthe register 174, to the power supply 146. The command sent to the powersupply 146 shuts the power supply 146 down. No power current is thenprovided to any one of the driver power connector pins 136P. A short onone of the electronic devices 82 (FIG. 3) will not cause damage to theelectronic device or other components of the burn-in board assembly 18.Such an individual over-current detection is very important, because thepower supply is rated at 200 A, which is relatively high when comparedto earlier systems that are rated around 25 A, which can result insignificant damage to the burn-in board in a short condition.

It can thus be seen that the system allows for high power currents to beprovided individually to each one of the electronic devices. Current isprovided individually to each one of the electronic devices, and isindividually monitored.

While certain exemplary embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative and not restrictive of the current invention, andthat this invention is not restricted to the specific constructions andarrangements shown and described since modifications may occur to thoseordinarily skilled in the art.

1. A driver assembly, comprising: a driver substrate; a plurality of driver signal connectors secured to the driver substrate, each driver signal connector having a surface for releasably mating with a respective signal contact and each driver signal connector to carry a maximum direct current having a first magnitude; signal electronics connected to the driver signal connectors; a plurality of driver power connectors secured to the driver substrate, each driver power connector having a surface for releasably mating with a respective power contact and each driver power connector to carry a maximum direct current having a second magnitude which is larger than the first magnitude; and a single power supply connected to the driver power connectors.
 2. The driver assembly of claim 1, wherein the second magnitude is at least 7 A.
 3. The driver assembly of claim 1, wherein the second magnitude is at least 1.5 times the first magnitude.
 4. The driver assembly of claim 1, wherein the second magnitude is at least 4 A more than the first magnitude.
 5. The driver assembly of claim 1, wherein the second magnitude is at least 7 A, at least 1.5 times the first magnitude, and at least 4 A more than the first magnitude.
 6. The driver assembly of claim 1, wherein the driver signal connectors and the driver power connectors are different types of connectors.
 7. The driver assembly of claim 6, wherein the driver signal connectors are within an edge finger connector block.
 8. The driver assembly of claim 7, wherein the surface of each driver power connector is substantially circular.
 9. The driver assembly of claim 8, wherein each driver power connector is a respective pin.
 10. The driver assembly of claim 1, wherein the driver signal connectors and the driver power connectors are in two distinct groups.
 11. The driver assembly of claim 10, further comprising: a driver power connector block, the driver power connectors being secured to the driver power connector block, and the driver power connector block being secured to the driver substrate independent from the driver signal connectors.
 12. The driver assembly of claim 11, further comprising: a driver power board, the driver power connector being secured to the driver power board and the driver power board being secured to the driver substrate independent from the driver signal connectors.
 13. The driver assembly of claim 1, wherein movement of the driver substrate in an insertion direction causes engagement of the driver signal connectors with the signal contacts and engagement of the driver power connectors with the power contacts.
 14. The driver assembly of claim 1, further comprising: a plurality of driver current detectors, each detector being in communication with a respective one of the driver power connectors to detect current separately through each one of the driver power connectors; and an output device in communication with the driver current detectors to provide an output of the respective currents through the respective driver power connectors.
 15. A driver assembly, comprising: a driver substrate; a plurality of driver signal connectors secured to the driver substrate, each driver signal connector having a surface for releasably mating with a respective signal contact; signal electronics connected to the driver signal connectors; a plurality of driver power connectors secured to the driver substrate, each driver power connector having a surface for releasable mating with a respective power contact; a power supply connected to the driver power connectors; a plurality of driver current detectors, each detector being in communication with a respective one of the driver power connectors to detect current separately through each one of the driver power connectors; and an output device in communication with the driver current detectors to provide an output of the respective currents through the respective driver power connectors.
 16. The driver assembly of claim 15, wherein power current provided by the power supply to a plurality of the driver power connectors is shut down if a current detected by a single driver current detector exceeds a predetermined maximum.
 17. The driver assembly of claim 16, wherein power current to at least 10 of the driver power connectors is shut down.
 18. The driver assembly of claim 16, wherein the power supply is shut down. 